/Engine/Source/Runtime/Core/Public/Math/UnrealMathUtility.h
Performs a 2D linear interpolation between four values values, FracX, FracY ranges from 0-1
template<typename T, typename U UE_REQUIRES> static constexpr T BiLerp ( const T & P00, const T & P10, const T & P01, const T & P11, const U & FracX, const U & FracY )